1. Field of the Invention
The present invention relates to an elongated sanitary napkin having a vagina-facing region and an intergluteal cleft-facing region elongated rearward thereof and more particularly to a sanitary napkin which can be kept curved while being in close contact with the wearer's body from the posterior part of the vagina to the intergluteal cleft so as to be effective in preventing rearward leakage of menstrual blood during sleep.
2. Description of the Related Art
Conventional sanitary napkins include ones having a protruding structure, which is intended to come into close contact with the wearer's body, on a skin-side surface of a napkin body containing a liquid absorbent layer.
Patent Publication 1 identified below discloses a sanitary napkin in which a longitudinally extending elastic member is provided between a liquid absorbent layer and a topsheet covering the skin-side surface of the liquid absorbent layer. The elastic member extends between front and rear edges of the sanitary napkin and exhibits an elastic contractive force to bring the front and rear edges of the sanitary napkin closer to each other, so that the sanitary napkin is curved to have its skin-side surface recessed and also the center of the topsheet is lifted away from the liquid absorbent layer because of the elastic member. By keeping the topsheet thus lifted away from the liquid absorbent layer in close contact with the wearer's body, menstrual blood is allowed to be absorbed by the liquid absorbent layer via the topsheet.
Patent Publication 2 identified below discloses a sanitary napkin in which a three-dimensional structure, which is formed of a liquid-permeable sheet to have a T-shaped cross-section, is provided on the skin-side surface of a napkin body. The three-dimensional structure has a front end adjacent to a front edge of the napkin body and a rear end adjacent to a rear edge of the napkin body. The three-dimensional structure is provided with elastic members for exhibiting a longitudinal contractive force. These elastic members exert a force to bring the front and rear edges of the napkin body closer to each other so that the napkin body is curved, which makes the three-dimensional structure rise from the skin-side surface of the napkin body. This three-dimensional structure can be kept in close contact with the female genital organ and is aimed at providing a pleasant feeling during wear.
Patent Publication 3 identified below discloses a sanitary napkin in which an absorbent body and a stiffening element is disposed between a topsheet and a liquid absorbent layer and a hump of a triangular cross-section is formed of the topsheet, the absorbent body and the stiffening element. In the sanitary napkin disclosed in Patent Publication 3, the hump can conform to the groove between the labia majora without giving an unpleasant feeling to a wearer.
Patent Publication 4 identified below discloses a sanitary napkin having a heaped protrusion in a rear region of a skin-side surface. From the description of Patent Publication 4, it is unclear how the protrusion is constituted, but it describes that the protrusion comes into contact with the cleft of the buttocks to prevent rearward leakage of menstrual blood.
Patent Publication 1: Japanese Unexamined Patent Publication No. 2000-83994
Patent Publication 2: Japanese Unexamined Patent Publication No. 2002-320638
Patent Publication 3: Japanese Unexamined Patent Publication No. 2001-504727
Patent Publication 4: Japanese Unexamined Patent Publication No. H11-42250
In Patent Publications 1 and 2, the napkin body has a relatively short length and the sanitary napkin is designed to generally centrally face the vagina and is aimed chiefly at bring the liquid-permeable sheet, which is raised by the elastic member, into close contact with the vaginal opening. However, such a sanitary napkin having a relatively short length tends to be less effective in preventing rearward leakage of menstrual blood and therefore is not suitable for use while sleeping.
Suitable for use while sleeping is a sanitary napkin which is elongated to have a rear portion enabled to face the buttocks. In the sanitary napkins disclosed in Patent Publications 1 and 2, however, since an elastic contractive force of the elastic member acts between the front and rear edges of the napkin body, if the sanitary napkin is so elongated as to be suitable for use while sleeping, the elastic contractive force will act almost over the entire length of the elongated napkin body. Therefore, it becomes difficult for the napkin body to keep a sufficient stiffness to resist the elastic contractive force, and when the elastic member is pushed by the wearer's body to increase the elastic contractive force, the liquid absorbent layer may be wrinkled and contracted longitudinally or even folded to lower adhesion between the napkin body and the wearer's body, which results in impairing the effect of preventing leakage of menstrual blood toward the buttocks and also in causing lateral leakage of menstrual blood.
In the sanitary napkin disclosed in Patent Publication 3, on the other hand, the hump having a triangular cross-section easily comes into close contact with the vagina but is not able to easily enter the intergluteal cleft. This is because the body's groove is relatively wide and shallow in a region from the vaginal opening to the anus, but relatively narrow and deep in the anus and the intergluteal cleft where the opposing surfaces of the buttocks are brought closer to each other. Moreover, since the hump is formed of the absorbent body and the stiffening element, the portion having the hump cannot be easily curved to follow the contour of the buttocks. Therefore, making the napkin body longer tends to create a clearance between the napkin body and the wearer's body.
In the sanitary napkin disclosed in Patent Publication 4, the construction of the protrusion remains unclear, but this protrusion having a triangular cross-section over the entire length thereof cannot easily come into close contact with the narrow, deep intergluteal cleft where the opposing surfaces of the buttocks are brought closer to each other although it can fit the vaginal opening and the wide, shallow groove near the vaginal opening.